The present invention relates to a system for conveying a liquid crystal display glass substrate (referred to as xe2x80x98LCD glass substrate conveyor systemxe2x80x99or merely as xe2x80x98conveyor systemxe2x80x99hereinafter).
In a processing system of the general type for processing LCD glass substrates, a plurality of processing devices such as a coater, a developer, an etching system and so forth are usually arranged side by side with the line of a LCD glass substrate conveyor system. In addition, in the LCD glass substrate conveyor system of the LCD glass substrate processing system, there is used an unmanned vehicle as called an Automatic Guided Vehicle (AGV) capable of freely walking around and visiting various processing devices accompanied by a cassette which holds approximately 20 sheets of the LCD glass substrates therein. So far, the LCD glass substrate has been formed to have such a size of 300 through 500 square millimeters at the largest. Therefore, it has been possible to hold a plurality of LCD glass substrates of such size in a cassette and to carry them together with the cassette by means of the AGV.
Recently, however, the LCD glass substrate is showing a tendency to grow larger, and even LCD glass substrates having a size of one square meter or more become available and used now. However, such larger LCD glass substrates causes such a new problem that they are apt to be bent when they are mounted on and held in the cassette. Thus, there has been caused such a problem that the cassette conveyance of LCD glass substrates by using AGV can not help receiving certain limitations from the standpoint of the size and weight of the LCD glass substrate itself.
Furthermore, the AGV is so expensive that the number of AGV""s allowed to use for one processing system is limited naturally. Therefore, the improvement of the working efficiency can not help encountering difficulty due to this limitation issue on the size and weight of the LCD glass substrate.
Still further, in order to comply with the randomness in the processing time by the processing system, there has been proposed a processing system of the other type, which is additionally provided with a buffering function for the LCD glass substrate. In order to add such buffering function, various ways have been proposed, for instance, a method for temporarily stopping the operation of the conveyor system. However, this method is not always desirable because it results in lowering the throughput. Another method is a method for adopting an exclusive space for enabling the buffering function for LCD glass substrates. However, when considering the tendency of the LCD glass substrate growing larger as describe above, this method would naturally invites the enlargement of the total area (referred to as xe2x80x98footprintxe2x80x99) needed for realizing the buffering function for LCD glass substrates. Accordingly, this would invite another issue to be solved after all.
The present invention has been made in view of such problems existing in the prior art LCD glass substrate conveyor system as described in the above. Therefore, the first object of the invention is to provide a novel and improved LCD glass substrate conveyor system, which is able to convey LCD glass substrates with ease regardless of the size and weight thereof.
Furthermore, the second object of the invention is to provide a novel and improved LCD glass substrate conveyor system, which can be set up without making use of any expensive device such as the AGV, thereby reducing the cost for constructing the processing system.
Still further, the third object of the invention is to provide a novel and improved LCD glass substrate conveyor system, which is able to add the buffering function for LCD glass substrates to the conveyor system without giving any influence over the throughput and footprint as well.
In order to solve such problems as described above, according to the first aspect of the invention, there is provided a LCD glass substrates conveyor system workable between a plurality of processing devices. This conveyor system comprises an outward conveyance means for conveying LCD glass substrates in the feeding direction between a plurality of processing devices; an inward conveyance means arranged to make a multi-storied structure together with the outward conveyance means for conveying LCD glass substrates in the return direction between a plurality of the processing devices; a vertical conveyance means for vertically conveying LCD glass substrates between the outward conveyance means and inward conveyance means, wherein the vertical conveyance means is provided with a plurality of conveyor tables for supporting LCD glass substrates from the underside thereof and moves up and down the conveyor tables such that they move linking to each other, and one of the conveyor tables forms a part of the outward conveyance means, another of the conveyor tables forms a apart of the inward conveyance means, and still another of the conveyor table forms a refuge portion for the LCD glass substitutes.
According to the structure of the conveyor system as described above, LCD glass substrates can be conveyed between processing devices by means of the multi-storied outward and inward conveyance means. Such outward and inward conveyance means are arranged at a predetermined interval and can be formed by a series of the substrate conveyance means, for instance conveyor rollers which support the LCD glass substrate from the underside thereof. Accordingly, this can easily comply with the tendency of the LCD glass substrate growing larger.
Furthermore, the structure of the above outward conveyance means and inward conveyance means can be produced at a very low cost comparing with the AGV having been used so far. Thus, the construction cost of the LCI) glass substrate conveyor system can be reduced to a great extent.
Since there is provided a refuge portion for saving LCD glass substrate from the outward and inward conveyance means, the buffering function for LCD glass substrate is added without stopping the operation of the outward and inward conveyance means. Thus, this prevents the throughput from being reduced. Furthermore, as the refuge portion is provided to stand in the vertical direction, any increase is not invited with regard to the foot print.
Still further, it is possible to provide a transfer arm for conveying the LCD glass substrate between the conveyor table forming the refuge portion for the LCD glass substrate of the vertical conveyance means and processing device. With this structure, while the LCD glass substrate staying in the refuge portion is treated in and returned from the processing device, one conveyor table of the vertical conveyance means forms a part of the outward conveyance means, and the other conveyor table forms a part of the inward conveyance means. As a result, the other LCD glass substrate can be conveyed to the other processing device to receive the other treatment without stopping the operation of the outward conveyance means and inward conveyance means.
Still further, the transfer arm may be constructed as follows. That is, the conveyor table is provided with a plurality of conveyor rollers for supporting the LCD glass substrate thereon. Therefore, the pick of the transfer arm can be inserted in a gap formed between the LCD glass substrate and plural rollers, thus the transfer arm being able to grasp and transfer the LCD glass substrate by making use of this gap.
The outward conveyance means, the inward conveyance means and vertical conveyance means respectively include portions some of which may be arranged in the atmospheric pressure area and the other has to be arranged in the vacuumed area. These portions respectively belonging to the different circumstances can be connected by way of a gate valve. With this structure, there can be realized the connection for connecting the outward conveyance means with the inward conveyance means across the atmospheric area and vacuumed area.
Furthermore, the vertical conveyance means has the function of switching the LCD glass substrate being conveyed in the return direction (feeding direction) to direct it in the feeding direction (return direction). This makes it possible to set up such treatment steps that have the LCD glass substrate treated by means of an identical processing device a plurality of times. In other words, the conveyor system can flexibly comply with variation or modification in the treatment steps, accordingly.
Still further, the outward conveyance means and inward conveyance means are respectively constructed such that they are provided with a series of substrate conveyance means which are arranged at a predetermined distance to support the LCD glass substrate from the underside thereof. Such substrate conveyance means can be equipped to be individually driven, respectively. Therefore, according to the structure of these outward conveyance means and inward conveyance means, it becomes possible to temporarily stop the LCD glass substrate conveyed by these outward or inward conveyance means. Thus, the LCD glass substrate can be directly taken out from the outward or inward conveyance means and be brought in the related processing device.
Still further, similar to the above, the conveyor table of the vertical conveyance means is provided with a series of substrate conveyance means which are arranged at a predetermined distance to support the LCD glass substrate from the underside thereof. Such substrate conveyance means can be equipped to be individually driven, respectively. Thus, the LCD glass substrate can be brought in the related processing device from the refuge portion thereof.
Still further, the LCD glass substrate can be conveyed in the state of being housed in a tray. Accordingly, the LCD glass substrate can be prevented from being bent even if it is enlarged in size and is increased in weight as well.
Still further, while LCD glass substrate is conveyed, it might possibly happen that the LCD glass substrate is charged electrostatically and/or it carries foreign bodies fitted thereto. If the LCD glass substrate is left as it is in such a state, an ill influence is given to the treatment thereof in the processing device. Therefore, it is preferable, as is done according to the invention, that an electrostatic charge remover means for eliminating electric charges and a foreign body remover means for preventing the foreign bodies from fitting on the LCD glass substrate are equipped with the refuge portion of the vertical conveyance means. As such a foreign body remover means, there can be used a clean air blower means or the like capable of blowing clean air against the LCD glass substrate.
Furthermore, if the LCD glass substrate is brought in the processing device from the refuge portion of the vertical conveyance means, delivery and acceptance of the LCD glass substrate between the processing device and conveyor system can be executed without causing any disturbance with respect to conveying of the other LCD glass substrates.